1 PST Heaters 4 panels per segment along pixel support tube. Each segment is 236mm long at the moment. Copper-on-kapton. Nominal 20 ohms per full panel. Laminated to 50 micron thick Al for EMI shield. Prototype testing indicated that bottom is coldest region => more redundancy on the bottom is desirable. Wires/segment as on sketch at right Center tap on bottom panel in case of failure on bottom panel (disconnect/reconnect externally to power ½ panel if failure) 2 top panels on adjacent segments are jumpered (except for one segment in barrel section) One segment On PST TOP Normally disconnected Externally

2 Prototype Layout Z IN OUT for Prototype OUT for Production Only for Prototype Center tap for spare connection Prototype PST section is longer than segments would be in production 236mm

3 Prototype Detail

4 Wires and Circuits 7 barrel segments. 2x10 end segments PST heater wires from barrel region 6x8+1x9 = 57. A-side is 3x8+1x9=33. C-side is 24 PST heater wires from end regions 2x10x8=160. A-side is 80 and C-side is 80. Not all wires are always connected. Barrel circuits(power supplies) = 25. End region circuits = 2 x 35 = 70 4 additional circuits to heat mounts to SCT Temperature sensor per panel=> 108 sensors + 4 for mount heaters. Total heater wires = = 225 Total circuits(power supply channels) = 99 Total temperature sensors = 112 => 224 wires